If I have a publisher node on one machine using ROS2 Humble and another subscriber node on a different machine using ROS2 Galactic, can they communicate?
My question is not on how to establish the ROS communication between two machines, but whether it is possible to run (e.g.) a talker with a different ROS version than the listener?
The answer to this is closer to “it depends”. ROS2 is not made so that different distros can reliably communicate with each other. That said, there is nothing specifically in place to disallow it either. Being built on DDS means communication can certainly work just fine, but this still provides no guarantee.
The short version is: it might work, but you shouldn’t expect it to with any sort of reliability.
